Cast
Mona Maris
Fraulein Lolita
William Collier Sr.
Mugs O'Flaherty (uncredited)
Harry Strang
Gunner and drill sergeant (uncredited)
Marion Lessing
Anna Marie Von Steuben
Hans Fuerberg
Fritz Kampf (Second Officer of U-172) (uncredited)
George Harris
Naval Reservist/Swimmer and Diver (uncredited)
Maurice Murphy
Merkel (uncredited)
Harry Tenbrook
Winkler (uncredited)
George O'Brien
Cmdr. Robert 'Bob' Kingsley
Larry Kent
Lt. 'Mac' McGregor
Ferdinand Schumann-Heink
Adolph Brucker (uncredited)
Henry Victor
Baron Ernst von Steuben (U-boat commander)
Walter C. Kelly
Chief Mike 'Guns' Costello
Warren Hymer
'Lug' Kaufman
Walter McGrail
Chief Joe Cobb
John Loder
Franz Shiller
Francis Ford
Eric - Captain of Trawler (uncredited)
Jack Murphy
Naval Reservist (uncredited)
Steve Pendleton
Ens. Richard 'Dick' Cabot (as Gaylord Pendleton)
Joseph Depew
Naval Reservist (uncredited)
Edward Peil Jr.
Naval Reservist (uncredited)
Nat Pendleton
'Butch' Wagner (uncredited)